nine16

I've been trying to solve a failure to get the 987.2 CS into "Ready" status for emissions testing for a bit now. (Catalyst Monitoring, Oxygen Sensors, Oxygen Sensor Heater, as in pic.) There are NO check engine lights or codes (according to 3 different but sub-PIWIS level scanners), just the persistent "Not Ready" statuses for the O2 sensor heater and 2 others. But, I figured the oxygen sensors were all original, so at 100k miles it was time.

Replaced the rears first since fronts were on backorder for a while. Did several of the advised drive cycles. Didn't help.

Rears finally arrived and swapped those a couple weeks ago. Tried 2 drive cycles that night, but no change.

I had already planned on cleaning the intake ports/valves since these are direct injection, and I had ordered a new AOS too, since it's easy to change out with the plenum and intake manifolds off anyway. Did all that and there was a decent amount of oil in the plenum, so the new AOS was a good idea. The rear intakes were actually quite clean on both banks, but ports were progressively worse toward the front cylinders. Didn't get to run (or drive cycle) the car because the brittle old plastic AOS hose broke. Put that on this week, did a couple of work commutes, then yesterday took the car up to the emptier roads of Wisconsin for about 150 miles, trying to use it in all the drive cycle conditions.

I don't know for sure if the new front sensors could have been the problem (and wouldn't have cleared after the two cycles mentioned). And while I'm sure de-carbonizing the intakes is a good thing, I believe that would only contribute to fouling the O2 sensors, which are the real, immediate cause for failing readiness. Perhaps I'm wrong though, and the carbonization was causing rich running and THAT is what kept the O2 sensors from reaching temp.

ive heard ru ors that it can take hundreds of miles to cycle (which seems absurd), but if if none reset soo am I looking at bad catalytic converters? Could the MAF be bad even with no codes??? Is there another possibility?

By the way, I have Capristo headers with the 250 cell cats. If that's the problem, can the old ceramic elements be replaced without junking the headers completely? I was told by the original owner there is no tune.

MrMoose

I couldn't get my sensors to the ready state either: 987.2 with about 80K. Like you there were no errors or warnings or anything. I ended up replacing all four oxygen sensors and that fixed the issue.

But that was with stock cats, couldn't tell you if your aftermarket cats could be contributing or worn out.

harveyf

There have been some fairly substantial threads here on this forum in the past on the subject of Ready Status. Most likely regarding 987.1 but probably worthing searching out.

What drive cycle are you using and where did you get it from? I can't recall the details but I went through this a year or so ago. The drive cycle that I found is pretty prescriptive. Something "idle for x seconds, drive between 25 and 35 mph for X minutes, drive between 45 and 55 mph for x minutes, stop and idle for x minutes. Repeat. It might be worth it to call the Service department at a dealership and see if they will give you the details.

nine16

The one I'm using is;
Cold start idle 2.5 minutes.
20-30 mph 3.5 minutes.
40-60 mph 15 minutes.
Idle in gear (PDK) 3 minutes.

Never exceed 3k rpm.

harveyf

Here is a link to a thread on Pelican:

https://forums.pelicanparts.com/pors...rocedures.html

MrMoose

I tried various drive cycles and just regular driving around for 2-3 weeks. Everything cleared except for the oxygen sensors. I replaced them and just drove normally for a couple days and they cleared. I suspect they were just getting old and reading slow: not enough to trip the CEL but enough to keep them from clearing.

Not saying that's definitely your issue but that was my experience (again, with stock cats).

harveyf

Those sound famililar to what I used.
I'm going into the dealership for parts. I'm going to ask the service manager about this. Surely it can't be a big secret, since it sounds like something they would coach the owners to do themselves.

nine16

Took it to a tuner yesterday, who confirmed that O2 sensors had been disabled. They are now enabled (with a new tune) and read on the diagnostic. There was one minor setback though--one of the 4 new O2 sensors is bad. It will arrive tomorrow and then Saturday I'll put some miles/drive cycles on it. Hopefully I can emissions test Saturday or Monday.